Probing the Spatial Distribution of Extrasolar Planets with Gravitational Microlensing

Astrophysics, abstract
astro-ph/0303317

From: cheongho@chungbuk.ac.kr

Date: Fri, 14 Mar 2003 01:02:57 GMT   (160kb)

Authors:
Cheongho Han (Chungbuk National University, Korea),
Young Woon Kang (Sejong University, Korea)

Comments: total 7 pages, including 4 figures, ApJ, submitted

Under the current microlensing planet search strategy of monitoring events
caused by stellar-mass lenses, only planets located within a narrow region of
separations from central stars can be effectively detected. However, with the
dramatic increase of the monitoring frequency, two additional populations of
free-floating and wide-orbit planets can be detected. In this paper, we
investigate the lensing properties of events caused by wide-orbit planets and
find that the light curves of a significant fraction of these events will
exhibit signatures of central stars, enabling one to distinguish them from
those caused by free-floating planets. Due to the large primary/planet mass
ratio, the effect of the central star endures to considerable separations. We
find that for a Jupiter-mass planet the signatures of the central star can be
detected with fractional deviations of > 5% from the best-fitting single-lens
light curves for > 80% of events caused by bound planets with separations < 10
AU and the probability is still substantial for planets with separations up to
20 AU. Therefore, detecting a large sample of these events will provide useful
information about the distribution of extrasolar planets around their central
stars. Proper estimation of the probability of distinguishing events caused by
wide-orbit planets from those caused by free-floating planets will be important
for the correct determination of the frequency of free-floating planets, whose
microlensing sample will be contaminated by wide-orbits planets.

References and citations for this submission:

SLAC-SPIRES HEP (refers to ,
cited by, arXiv reformatted)